A known electric oil pump apparatus has been disclosed in a Japanese Patent Laid-Open published as No. H11(1999)-173278. The disclosed electric oil pump apparatus includes a drive rotor shaft, of which both ends are supported by bearings in a pump housing, and a motor rotation shaft of which both ends are supported by bearings in a motor housing. The drive rotor shaft and the motor rotation shaft are axially connected via a jointing portion. A motor driving force is transmitted to the drive rotor shaft via the jointing portion and a drive rotor is rotated in response to rotation of the drive rotor shaft, thereby oil in the pump housing can be fed being applied with a pressure. Therefore, the disclosed electric oil pump apparatus functions as an oil pump apparatus in which the oil is inhaled from an oil suction port defined in the pump housing and is discharged from an oil discharging port defined therein.
However, the disclosed oil pump apparatus may have following problems to be solved. The drive rotor shaft and the motor rotation shaft axially arranged are connected by means of a jointing portion. In this case, an axial length of the electric oil pump apparatus becomes longer and mechanical loss may occur with the jointing portion. Further, each shaft requires two bearings to be supported at both ends thereof so that the number of assemblies in the oil pump apparatus may be increased. Therefore, the disclosed electric oil pump apparatus seems to possess a relatively complicated structure.
The present invention therefore seeks to provide an improved electric oil pump apparatus of which structure is relatively simple.